This disclosure relates generally to the field of image processing and, more particularly, to various techniques to generate noise-constrained tone curves for use in real-time image processing.
Tone mapping is the process of remapping gray levels from a first or input image to different levels in a second or output image. Tone mapping is generally used to adjust the input image to more closely match the visual appearance anticipated by the human eye on a particular output device, and/or to better preserve image information when mapping an input image to a smaller output dynamic range. Global tone mapping refers to the situation where there is a single tone curve that maps input gray levels to output gray levels. Local tone mapping refers to the case where a single gray level in the input image maps to multiple gray levels in the output image depending on the spatial location and configuration of the input image. Tone mapping is used in almost all image processing pipelines, but is of particular importance when rendering high dynamic range images for a limited dynamic range output device (e.g., created for example by fusing multiple exposures). Illustrative devices having a limited output dynamic range include most consumer desktop and portable displays.